It is desirable in automated chemical analyzers to store several reagents in contiguous compartments or vessels. Such a common multicompartment container is sold today for use in an instrument known as the Dimensio.TM. Chemical Analyzer by E. I. du Pont de Nemours and Company. Wilmington Del. This multicompartmented container is in the form of a container strip which is described in U.S. Pat. No. 4,720,374 entitIed "Container Having a Sonication Compartment". issued to Ramachandran includes a rigid peripheral band formed of an inert plastic. The band is formed integrally with each of the containers such that the container strip generally tapers in a substantially elongated wedge-like manner from a first edge to a second edge. The wedge-shaped plan profile for the container strip facilitates the mounting of a plurality of such strips in a circumferentially adjacent generally radially extending relationship across a rotatable reagent carrying plate. The tops of the containers are sealed with a suitable laminate that prevents gas and vapor escape and yet permits penetration by a probe for aspiration etc. The plastic used for the receptacle is polyethylene and the laminate is a three-ply laminate of a polyester film, a polyvinylidene chloride coating on the polyester film, and finally a sheet of polyethylene adhered to the coating. The laminate is heat sealed to the peripheral surface of the polyethylene compartments with the lower polyethylene sheet contacting the compartment rim.
When storing a liquid reagent or specimen care must be exercised to minimize evaporation. Simultaneously, however whatever structure is used to inhibit evaporation must be compatible with the requirement of access to the liquid as by an aspirating probe during use. The Ramachandran U.S. Pat. No. 4,720,374 entitled "Container Having a Sonication Compartment" describes such a lid which reduces air and vapor transmission through the top of the lid. By isolating the compartments and thereby forming multicompartmented containers, contamination between compartments is also reduced. The lid structure described is formed of conjoined upper and lower sheets of material. The lower sheet is polyethylene and has a receptacle formed therein which receives an elastomeric self-healing pad. The upper sheet is a laminate as described above and the pad is sandwiched between the upper and lower sheets. The portion of the conjoined first and second sheets forms a sealing flange which completely surrounds the periphery of the receptacle and which provides a surface whereby the lid may be secured to the container.
While providing excellent storage for reagents the container strip does not always inhibit evaporative losses after its lid has been punctured by a probe sufficiently to permit its use for the long term on instrument storage of reagents, particularly heterogeneous immunoassay reagents. To facilitate long term or instrument storage the evaporation through the laminate should be less than one milligram per day. Such a low rate would permit even such immunoassay reagents to be stored for more than ten days on the instrument. Such low evaporation must subsist despite repeated puncturing of the laminate for the aspiration of fluids.
It is known that creating a vortex in the fluid contained in a compartment is an effective means for mixing the contents of the vessel. Common laboratory vortexers use a support cup or a resilient compartment receiving surface mounted eccentrically to a motor in order to translate the compartment in a circular path or orbit at a high speed and thereby create an effective vortex in the fluid contained in the compartment. Exemplary of this type of device are those disclosed in U.S. Pat. Nos. 4,555,183 (Thomas) and 3,850,580 (Moore et al.). These devices are manual in that an operator is required to hold the compartment in contact with the eccentrically movable means to create the vortex in the fluid disposed in the compartment.
Such vortex type mixer would be extremely advantageous in an automated chemical analysis instrument as it is noninvasive and therefore can avoid the concern of contamination associated with an improperly cleaned invasive mixing means.
Unfortunately, when the bottom of a vessel or compartment is orbited to create a vortex, it is difficult to maintain the compartment's lid structure sealed. This is particularly true when these are multicompartments and one is orbited and the others remain stationary.